- Preheat oven to 375°.
- Place potatoes in a large pot; cover with cold water to 2 inches above potatoes. Bring to a boil; reduce heat, and simmer 15 minutes or until very tender. Drain; place in a large bowl.
- Heat oil and butter in a medium skillet over medium heat until butter melts.
- Add 2 tablespoons sugar, vanilla, 1 teaspoon salt, cinnamon, and milk to potatoes. Beat with a mixer at medium speed until smooth.
- Spoon potato mixture into an 11 x 7-inch baking dish coated with cooking spray.
- Add oats, pecans, flour, remaining 1/4 cup sugar, and remaining 1/4 teaspoon salt to butter mixture; toss. Sprinkle over potato mixture.
- Bake at 375° for 35 minutes or until bubbly around the edges.